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SAE International Journal of Passenger Cars Mechanical Systems
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Vehicle Stability Control through Optimized Coordination of Active Rear Steering and Differential Driving/Braking

SAE International Journal of Passenger Cars - Mechanical Systems

Dongfeng Motor Corporation-Zhao Yachao
SAIC-GM Wuhan Branch-Fang Cheng
  • Journal Article
  • 06-11-03-0020
Published 2018-07-05 by SAE International in United States
In this article, a hierarchical coordinated control algorithm for integrating active rear steering and driving/braking force distribution (ARS+D/BFD) was presented. The upper-level control was synthesized to generate the required rear steering angle and external yaw moment by using a sliding-mode controller. In the lower-level controller, a control allocation algorithm considering driving/braking actuators and tire forces constraints was designed to assign the desired yaw moment to the four wheels. To this end, an optimization problem including several equality and inequality constraints were defined and solved analytically. Finally, computer simulation results suggest that the proposed hierarchical control scheme was able to help to achieve substantial enhancements in handling performance and stability. Moreover, the comparison between ARS+D/BFD and AFS+D/BFD (active front steering and driving/braking force distribution) by using the proposed controller was presented and analyzed.
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Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions

SAE International Journal of Passenger Cars - Mechanical Systems

Max Varney, Martin Passmore, Adrian Gaylard
  • Journal Article
  • 06-11-03-0018
Published 2018-06-28 by SAE International in United States
Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design and practicality, which is not typically aerodynamic. Drag can be reduced with a number of passive and active methods, which are generally prioritised at zero yaw, which is not entirely representative of the “on road” environment. As such, to combine a visually square geometry (at rest) with optimal drag reductions at non-zero yaw, an adaptive system that applies vertical side edge tapers independently is tested statically. A parametric study has been undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor Model. The aerodynamic effect of implementing asymmetric side tapering has been assessed for a range of yaw angles (0°, ±2.5°, ±5° and ±10°) on the force and moment coefficients. This adaptive system reduced drag at every non-zero yaw angle tested, from the simplest geometry (full body taper without wheels) to the most complex geometry (upper body taper with wheels) with varying levels of success; providing additional drag reductions from 3% to 125%. The system also shows potential to beneficially modify…
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Evaluation of the Energy Consumption of a Thermal Management System of a Plug-In Hybrid Electric Vehicle Using the Example of the Audi Q7 e-tron

SAE International Journal of Passenger Cars - Mechanical Systems

AUDI AG-Jan Christoph Menken, Klaus Strasser, Thomas Anzenberger, Christian Rebinger
  • Journal Article
  • 06-11-03-0017
Published 2018-06-18 by SAE International in United States
The transition of vehicle propulsion technologies away from conventional internal combustion engines toward more electrically dominant systems such as plug-in hybrid electric vehicles (PHEV) poses new challenges for vehicle thermal management systems. Especially at low ambient temperatures, consumer demand for cabin comfort as well as legislatively imposed safety considerations significantly reduce the electric driving range because only electric energy can be used for heating during emissions-free driving modes. Recent developments to find energy efficient thermal management systems for electric and plug-in electric vehicles have led to the implementation of automotive heat pump systems. As an alternative approach to meet dynamic heating demands and safety regulations, these systems use heat at a low temperature level, for example the waste heat of electric drivetrain components, to heat the passenger compartment efficiently and therefore increase the electric driving range. Under moderate and humid environmental conditions, thermal management systems operate in a so called reheat mode. This safety-relevant reheat mode is characterized by the cooling and resulting dehumidification of the in-stream air and the subsequent heating to maintain cabin…
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Exhaust Manifold Thermal Assessment with Ambient Heat Transfer Coefficient Optimization

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Otomotiv Sanayi AS-Baran Celikten, İpek Duman, Caner Harman, Sinan Eroglu
  • Journal Article
  • 06-11-03-0016
Published 2018-06-04 by SAE International in United States
Exhaust manifolds are one of the most important components on the engine assembly, which is mounted on engine cylinder head. Exhaust manifolds connect exhaust ports of cylinders to the turbine for turbocharged diesel engine therefore they play a significant role in the performance of engine system. Exhaust manifolds are subjected to very harsh thermal loads; extreme heating under very high temperatures and cooling under low temperatures. Therefore designing a durable exhaust manifold is a challenging task. Computer aided engineering (CAE) is an effective tool to drive an exhaust manifold design at the early stage of engine development. Thus advanced CAE methodologies are required for the accurate prediction of temperature distribution. However, at the end of the development process, for the design verification purposes, various tests have to be carried out in engine dynamometer cells under severe operating conditions. The test running durations up to 2500 hours are required for the heavy duty (HD) diesel engine exhaust manifold; therefore they are very expensive and time consuming. In order to avoid this additional costs, having first time…
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Comparison of Various Drag Reduction Devices and Their Aerodynamic Effects on the DrivAer Model

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai Motor Company-Hak-Lim Kim
Seoul National University-Junho Cho, Joonmin Park, Kwanjung Yee
  • Journal Article
  • 06-11-03-0019
Published 2018-07-05 by SAE International in United States
In this study, two types of drag reduction devices (a horizontal plate, and a vertical plate) are used to weaken the downwash of the upper flow and c-pillar vortex of the DrivAer notchback model driving at high speed (140 km/h). By analyzing and comparing 15 cases in total, the aerodynamic drag reduction mechanism can be used in the development of vehicles. First, various CFD simulation conditions of a baseline model were compared to determine the analysis condition that efficiently calculates the correct aerodynamic drag. The vertical plate and horizontal plate applied in the path of the c-pillar vortex and downwash suppressed vortex development and induced rapid dissipation. As a result, the application of a 50-mm wedge-shaped vertical plate to the trunk weakened the vortex and reduced the drag by 3.3% by preventing the side flow from entering the trunk top. The installation of a 150 mm horizontal plate at the trunk to decrease downwash reduced the drag by 5.1% by improving the bottom and side flow.
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